Why are my carrots not sizing up?

The most likely cause for stunted carrots is compaction or poor-quality soil. 

Have you ever sowed carrots and followed all the advice you could find only to harvest carrots with no length or girth? 

Let’s take a deeper dive into what you can do to get better carrots and root crops in general.  

Weeds

Carrots are quite difficult to grow without sprouting other weeds in their place. The carrot seed itself takes about a week to germinate depending on your local conditions. This is a much slower germination rate compared to many spring and summer weeds or grasses that will jump at the opportunity to fill in any open space you created with your carrot beds.  

Even after germination, carrots are quite slow to start growing and distinguish themselves from similar-looking seedlings. Having the right tools to kill our weeds will also take care of the main issue of compaction.  

Spacing

Planting carrots too closely will also affect carrot sizing. Follow the information provided on your seed packet regarding spacing as it can differ based on the type of carrots. On my farm, we generally grow a 3-row spacing of carrots, spaced 15″ apart row-to-row, and do not thin our carrots. When planting, we sow about 15-30 seeds per foot or 3/4″-2″ apart. Usually the wider the spacing the larger the roots. But more important is to keep the beds free of compaction. I will often pull out lots of great sized carrots 1/2″ apart or less.

Compaction

When our gardens get compacted all of our crops are going to underperform. You will especially notice this with root crops that form deep taproots such as carrots or parsnips.  

Causes of compaction

1. Heavy Machinery- It is a good idea to avoid having heavy machinery where we are growing vegetables.  
2. Rain- Rain is the most common, uncontrollable factor that causes compaction in the garden. If you live in a region like Virginia that often receives heavy rain, you may have noticed how hard the ground looks after rain.   
3. Excessive foot traffic on bedtops- Excessive weight especially when the ground is wet will damage the soil structure and impact gas exchange near the plants.

Fertilization

Over-fertilization can also be a reason that our carrots develop poorly. Carrots tend to form lots of root hairs and grow excessive greens when too much nitrogen is added to fertilizers. When looking at the N-P-K numbers on a fertilizer or amendment be sure to avoid a high N or K number. Something like a bone meal a 2-14-0 would be ideal to help send your carrots to ideal sizing and avoid hairs on the carrot.  

Varieties

Our last consideration will be considering varieties to plant. If you are homesteading and want to save your seeds stick to heirloom varieties. If you are growing for the market there are some great hybrid varieties on the market now with better heat tolerance and holding ability. Especially when you grow spring carrots in a warm region, growing carrots without great holding ability means they will most likely flower and become unappealing in taste too quickly. 

Seed Types

You can buy raw seeds or pelleted seeds. I have found that pelleted seeds tend to dry out quicker once planted and need optimum soil moisture about 1″ deep. Not allowing the soil to dry out during germination is very important for good seed germination rates.

The other issue with pelleted seeds is that the germination rates will significantly decline the longer they are stored. Only buy pelleted seeds from reputable seed suppliers. Buy raw seed if you hope to use the same seed for spring and summer-planted fall-harvested carrots.  

Solutions

To effectively grow nice carrots we want to either cultivate or add mulch to prevent compaction. 

Cultivation

Cultivation is the practice of breaking up the soil no more than 1″ below the surface. This can be performed with blades and tractors or with hand tools such as a wire hoe or oscillating hoe.  

How often to cultivate

It’s ideal to cultivate around once a week. There is an ideal time to cultivate when the soil is not at field capacity, (or saturated), but rather when it is about to dry in the top inch that you want to cultivate. The act of cutting that top layer of soil or compost breaks up the surface tension or compaction that we received from the heavy rains. Now that there is no downward pressure on the soil we will only lose water through evapotranspiration through plants and not through evaporation from bare soil. Cultivating now formed a soil mulch that allows for gas exchange. We want to keep oxygen in our soil and we also have access to free Nitrogen from the air when there are proper air ratios in our soil. 

Depending on the spacing of your carrots you possibly do not need to cultivate after your carrots have closed the canopy where you planted them. This cover will prevent compaction and you will also have a harder time cultivating without pulling out carrots.   

Mulch

Another method to avoid compaction is to apply an inch or more of compost to a bed before planting. Having compost as a mulch will help break up some of the expected compaction and make it easier to cultivate as well.  

I wouldn’t advise eliminating cultivation because the other benefit of cultivation is that you are killing young emerging weeds. The golden rule for cultivation is early and often. Just because you don’t see weeds doesn’t mean they aren’t germinating below the surface. Relying on the soil moisture to indicate when to cultivate is how we operate on our farm. Weeds will respond to rain events as well, so it only makes sense.